Translating B cell immunology to the treatment of antibody-mediated allograft rejection

Antibody-mediated rejection (AMR), including chronic AMR (cAMR), causes ~50% of kidney allograft losses each year. Despite attempts to develop well-tolerated and effective therapeutics for the management of AMR, to date, none has obtained FDA approval, thereby highlighting an urgent unmet medical need. Discoveries over the past decade from basic, translational and clinical studies of transplant recipients have provided a foundation for developing novel therapeutic approaches to preventing and treating AMR and cAMR. These interventions are aimed at reducing donor-specific antibody levels, decreasing graft injury and fibrosis, and preserving kidney function. Innovative approaches emerging from basic science findings include targeting interactions between alloreactive T cells and B cells, and depleting alloreactive memory B cells, as well as donor-specific antibody-producing plasmablasts and plasma cells. Therapies aimed at reducing the cytotoxic antibody effector functions mediated by natural killer cells and the complement system, and their associated pro-inflammatory cytokines, are also undergoing evaluation. The complexity of the pathogenesis of AMR and cAMR suggest that multiple approaches will probably be required to treat these disease processes effectively. Definitive answers await results from large, double-blind, multicentre, randomized controlled clinical trials.

TIMP-2 and IGFBP7 in human kidney biopsies in renal disease

Background

Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) are markers of tubular stress and urinary [TIMP-2]*[IGFBP7] is an established biomarker for risk assessment of acute kidney injury. There are no studies of expression profiles or localization of these markers in human renal tissue with confirmed renal disease.

Methods

We analysed 37 kidney biopsies of patients with renal disease and 10 non-diseased control biopsies for TIMP-2 and IGFBP7 expression using immunohistochemistry. Changes in glomerular morphology were evaluated by a semi-quantitative glomerulosclerosis score (GSI) and tubular interstitial changes were graded by the tubular injury score (TSI) using periodic acid-Schiff-stained paraffin sections. Interstitial fibrosis and tubular atrophy (IF/TA) were graded according to the Banff classification. Urinary [TIMP-2]*[IGFBP7] was collected at the time of biopsy.

Results

TIMP-2 and IGFBP7 had significantly greater expression in kidney biopsies from patients with renal disease compared with control tissue, especially in the tubular compartment. Here, IGFBP7 was detected in proximal and distal tubules while TIMP-2 was predominantly localized in the collecting ducts. Renal injury significantly correlated with staining intensity for TIMP-2 and IGFBP7: GSI weakly correlated with glomerular TIMP-2 (r = 0.36) and IGFBP7 (r = 0.35) and TSI correlated with tubular TIMP-2 (r = 0.41) and IGFBP7 (r = 0.43). Urinary [TIMP-2]*[IGFBP7] correlated weakly with the histopathological damage score but not with glomerular and tubular expression.

Conclusion

Our findings underline the role of TIMP-2/IGFBP7 as an unspecific marker of renal injury that is already in use for early detection of acute kidney injury.

Experimental renal transplantation in rats improves cardiac dysfunction caused by chronic kidney disease while LVH persists

Background

Chronic kidney disease (CKD) causes congestive heart failure (CHF) with systolic dysfunction and left ventricular hypertrophy (LVH), which is a major contributor to increased mortality in CKD patients. It remains unclear whether cardiovascular changes that occur during the course of CKD can be reversed when renal function is restored by transplantation.

Methods

To investigate this, chronic kidney disease was established in F344 rats by subtotal nephrectomy (SNx) for 8 weeks, followed by transplantation of a functional kidney from an isogenic F344 donor. SNx rats without transplantation and sham-operated animals served as controls. Renal function was assessed before and throughout the experiment. In addition, cardiac ultrasound was performed at weeks 0, 8, 12 and 16. At the end of the experiment, intra-arterial blood pressure was measured and kidneys and hearts were histologically and molecularly examined.

Results

Eight weeks after SNx, rats developed marked renal dysfunction associated with significant glomerulosclerosis and tubulointerstitial fibrosis, but also an increase in left ventricular mass. After transplantation, renal function normalized but relative heart weight and ventricular mass as assessed by ultrasound scans showed no reduction compared with SNx controls. However, left ventricular wall thickness, fractional shortening and ejection fraction was normalized by renal transplantation. At 8 weeks after kidney transplantation, cardiac expression of BNP and FGF23 was also at levels comparable to healthy controls, whereas these factors were significantly increased in SNx rats. Cardiac fibrosis, as measured by fibronectin mRNA expression, was completely normalized, whereas cardiac fibronectin protein was still slightly but not significantly increased in transplanted animals compared to controls. In addition, the myofibroblast marker collagen 1, as assessed by immunohistochemistry, was significantly increased in SNx rats and also normalized by renal transplantation. Interestingly, CD68+ macrophages were significantly reduced in the hearts of SNx rats and in transplanted animals at slightly higher levels compared to controls.

Conclusion

Restoration of renal function by kidney transplantation normalized early cardiac changes at most functional and molecular levels, but did not completely reverse LVH. However, further studies are needed to determine whether restoration of renal function can also reverse LVH at a later time point.

Complement Activation via the Lectin and Alternative Pathway in Patients With Severe COVID-19

Complement plays an important role in the direct defense to pathogens, but can also activate immune cells and the release of pro-inflammatory cytokines. However, in critically ill patients with COVID-19 the immune system is inadequately activated leading to severe acute respiratory syndrome (SARS) and acute kidney injury, which is associated with higher mortality. Therefore, we characterized local complement deposition as a sign of activation in both lungs and kidneys from patients with severe COVID-19. Using immunohistochemistry we investigated deposition of complement factors C1q, MASP-2, factor D (CFD), C3c, C3d and C5b-9 as well as myeloperoxidase (MPO) positive neutrophils and SARS-CoV-2 virus particles in lungs and kidneys from 38 patients who died from COVID-19. In addition, tissue damage was analyzed using semi-quantitative scores followed by correlation with complement deposition. Autopsy material from non-COVID patients who died from cardiovascular causes, cerebral hemorrhage and pulmonary embolism served as control (n=8). Lung injury in samples from COVID-19 patients was significantly more pronounced compared to controls with formation of hyaline membranes, thrombi and edema. In addition, in the kidney tubular injury was higher in these patients and correlated with lung injury (r=0.361*). In autopsy samples SARS-CoV-2 spike protein was detected in 22% of the lungs of COVID-19 patients but was lacking in kidneys. Complement activation was significantly stronger in lung samples from patients with COVID-19 via the lectin and alternative pathway as indicated by deposition of MASP-2, CFD, C3d and C5b9. Deposits in the lung were predominantly detected along the alveolar septa, the hyaline membranes and in the alveolar lumina. In the kidney, complement was significantly more deposited in patients with COVID-19 in peritubular capillaries and tubular basement membranes. Renal COVID-19-induced complement activation occurred via the lectin pathway, while activation of the alternative pathway was similar in both groups. Furthermore, MPO-positive neutrophils were found in significantly higher numbers in lungs and kidneys of COVID-19 patients and correlated with local MASP-2 deposition. In conclusion, in patients who died from SARS-CoV-2 infection complement was activated in both lungs and kidneys indicating that complement might be involved in systemic worsening of the inflammatory response. Complement inhibition might thus be a promising treatment option to prevent deregulated activation and subsequent collateral tissue injury in COVID-19.

Interferon-α exerts proinflammatory properties in experimental radiation-induced esophagitis: Possible involvement of plasmacytoid dendritic cells

AIMS

Radiation-induced esophagitis, experienced during radiation therapy for lung cancer and head and neck cancer, is a major dose-limiting side effect of the treatment. This study aimed to elucidate the role of interferon-α (IFN-α) in radiation-induced esophagitis.

MAIN METHODS

C57BL/6 mice were exposed to 10 and 25Gy of single thoracic irradiation. Esophageal mucosal damage and inflammatory reactions were assessed for 5 days after irradiation.

KEY FINDINGS

Irradiation induced esophagitis, characterized by reduction in the thickness of epithelial layer, upregulation of proinflammatory cytokines and chemokines, infiltration of inflammatory cells into the esophageal mucosa, and apoptosis of epithelial cells. Irradiation upregulated the level of gene expression for IFN-α in the esophageal tissue, and the neutralizing antibody against IFN-α ameliorated radiation-induced esophageal mucosal damage, while administration of IFN-α receptor agonist (RO8191) had an inverse effect. Depletion of plasmacytoid dendritic cells (pDCs) by anti-CD317 antibody or pharmacological inactivation with bortezomib suppressed radiation-induced mucosal inflammation and damage, accompanied by decrease in IFN-α expression level.

SIGNIFICANCE

These findings suggest that IFN-α and pDCs exert proinflammatory properties in the pathophysiology of radiation-induced esophagitis.

Bortezomib in autoimmune hemolytic anemia and beyond

Bortezomib is a first-in-class, potent, selective and reversible proteasome inhibitor approved for the treatment of multiple myeloma (MM) and relapsed/refractory mantle cell lymphoma. In these diseases, bortezomib targets plasma cells and lymphocytes reducing tumor burden. Recently, preclinical evidence highlighted its efficacy in reducing long-lived plasma cells responsible of autoantibodies production in several models of autoimmune conditions. These findings paved the way to a number of experiences of bortezomib use in patients with various autoimmune conditions, including autoimmune hemolytic anemia (AIHA). The latter is a nice model of autoimmunity in hematology and is caused by the production of autoantibodies against erythrocytes resulting in various degrees of hemolytic anemia. AIHA is classified in warm and cold forms according to the thermal characteristics of the autoantibody, and first-line treatment mainly relies on steroids for warm cases and the anti-CD20 rituximab for cold ones. Relapsed/refractory cases are still an unmet need, and bortezomib has been proposed in this setting with intriguing efficacy. In this review, we collected available literature on bortezomib use in AIHA and in other immune-mediated hematologic and non-hematologic diseases. Overall, most experiences highlight bortezomib efficacy even in multi-relapsed/refractory patients and suggest to consider its use in AIHA after rituximab failure.

Bortezomib: a proteasome inhibitor for the treatment of autoimmune diseases

Autoimmune diseases (ADs) are conditions in which the immune system cannot distinguish self from non-self and, as a result, tissue injury occurs primarily due to the action of various inflammatory mediators. Different immunosuppressive agents are used for the treatment of patients with ADs, but some clinical cases develop resistance to currently available therapies. The proteasome inhibitor bortezomib (BTZ) is an approved agent for first-line therapy of people with multiple myeloma. BTZ has been shown to improve the symptoms of different ADs in animal models and ameliorated symptoms in patients with systemic lupus erythematous, rheumatoid arthritis, myasthenia gravis, neuromyelitis optica spectrum disorder, Chronic inflammatory demyelinating polyneuropathy, and autoimmune hematologic diseases that were nonresponsive to conventional therapies. Proteasome inhibition provides a potent strategy for treating ADs. BTZ represents a proteasome inhibitor that can potentially be used to treat AD patients resistant to conventional therapies.

Complement in Renal Disease as a Potential Contributor to Arterial Hypertension

OBJECTIVE

Complement deposition is prevalent in kidney biopsies of patients with arterial hypertension and hypertensive nephropathy, but an association of hypertension and complement deposition or involvement of complement in the pathogenesis of hypertensive nephropathy has not been shown to date.

METHODS

In this study, we analyzed complement C1q and C3c deposition in a rat model of overload and hypertension by subtotal nephrectomy (SNX) and in archival human renal biopsies from 217 patients with known hypertension and 91 control patients with no history of hypertension using semiquantitative scoring of C1q and C3c immunohistochemistry and correlation with parameters of renal function. To address whether complement was only passively deposited or actively expressed by renal cells, C1q and C3 mRNA expression were additionally analyzed.

RESULTS

Glomerular C1q and C3c complement deposition were significantly higher in kidneys of hypertensive SNX rats and hypertensive compared to nonhypertensive patients. Mean arterial blood pressure (BP) in SNX rats correlated well with the amount of glomerular C1q and C3c deposition and with left ventricular weight, as an indirect parameter of high BP. Quantitative mRNA analysis showed that C3 was not only deposited but also actively produced by glomerular cells of hypertensive SNX rats and in human renal biopsies. Of note, in patients CKD-stage correlated significantly with the intensity of glomerular C3c staining, but not with that of C1q.

CONCLUSION

Renal complement deposition correlated with experimental hypertension as well as the presence of hypertension in a variety of renal diseases. To answer the question, if and how exactly renal complement is causative for the pathogenesis of arterial hypertension in men, further studies are needed.

Proteasome Inhibitors Bortezomib and Carfilzomib Stimulate the Transport Activity of Human Organic Anion Transporter 1

Organic anion transporter 1 (OAT1), expressed at the basolateral membrane of renal proximal tubule epithelial cells, mediates the renal excretion of many clinically important drugs. Previous study in our laboratory demonstrated that ubiquitin conjugation to OAT1 leads to OAT1 internalization from the cell surface and subsequent degradation. The current study showed that the ubiquitinated OAT1 accumulated in the presence of the proteasomal inhibitors MG132 and ALLN rather than the lysosomal inhibitors leupeptin and pepstatin A, suggesting that ubiquitinated OAT1 degrades through proteasomes. Anticancer drugs bortezomib and carfilzomib target the ubiquitin-proteasome pathway. We therefore investigate the roles of bortezomib and carfilzomib in reversing the ubiquitination-induced downregulation of OAT1 expression and transport activity. We showed that bortezomib and carfilzomib extremely increased the ubiquitinated OAT1, which correlated well with an enhanced OAT1-mediated transport of p-aminohippuric acid and an enhanced OAT1 surface expression. The augmented OAT1 expression and transport activity after the treatment with bortezomib and carfilzomib resulted from a reduced rate of OAT1 degradation. Consistent with this, we found decreased 20S proteasomal activity in cells that were exposed to bortezomib and carfilzomib. In conclusion, this study identified the pathway in which ubiquitinated OAT1 degrades and unveiled a novel role of anticancer drugs bortezomib and carfilzomib in their regulation of OAT1 expression and transport activity. SIGNIFICANCE STATEMENT: Bortezomib and carfilzomib are two Food and Drug Administration-approved anticancer drugs, and proteasome is the drug target. In this study, we unveiled a new role of bortezomib and carfilzomib in enhancing OAT1 expression and transport activity by preventing the degradation of ubiquitinated OAT1 in proteasomes. This finding provides a new strategy in regulating OAT1 function that can be used to accelerate the clearance of drugs, metabolites, or toxins and reverse the decreased expression under disease conditions.

Efficacy and safety of bortezomib in refractory lupus nephritis: a single-center experience

BACKGROUND AND OBJECTIVES

Resistant lupus nephritis (LN) has been associated with the persistence of long-lived plasma cells. Preliminary studies identified bortezomib as a potential treatment option for patients with refractory LN. The aim of this study was to analyze the efficacy and safety of bortezomib in the treatment of severe refractory LN.

METHODS

This retrospective study included 12 female patients diagnosed for the first time with class IV or IV/V LN with acute or rapidly progressive kidney injury (n = 11) and/or severe nephrotic syndrome (n = 1) who showed resistance to induction therapy with cyclophosphamide, steroids, mycophenolate, and rituximab, and were treated with either intravenous or subcutaneous bortezomib plus intravenous dexamethasone.

RESULTS

All patients with acute or rapidly progressive kidney injury showed a significant reduction in both biochemical and immunological activity after a mean of 6 (minimum 5, maximum 7) weekly cycles of bortezomib regimen, with a significant increase in C3 levels and a significant decrease of anti-ds DNA antibody titers, Systemic Lupus Erythematosus Disease Activity Index score, serum creatinine, and proteinuria. One patient (8.3%) achieved a complete response, and 10 patients (83.4%) achieved a partial response. During follow-up, all these patients maintained partial responses under treatment with mycophenolate and low-dose glucocorticoids. The patient with refractory nephrotic syndrome showed a partial response but relapsed 11 months after the end of bortezomib treatment and was resistant to treatment. A significant decrease in serum IgG levels after initiation of bortezomib treatment was observed in all patients, five of them (41.6%) showed hypogammaglobulinemia (<500 mg/dl), but no patient suffered from opportunistic infections; in only two patients (16.6%) hypogammaglobulinemia persisted at the end of follow-up. Two patients (16.6%) suffered from sensory neuropathy, which led to bortezomib treatment discontinuation.

CONCLUSIONS

Bortezomib may be an effective option for refractory LN, but close monitoring must be performed for possible adverse events such as peripheral neuropathy and hypogammaglobulinemia.

Series test of cluster and network analysis for lupus nephritis, before and after IFN-K-immunosuppressive therapy

AIM

The purpose was to screen potential targets of IFN-K-immunosuppressive therapy, which was used to offer effective information and resources for molecular targeted therapy.

METHODS

The gene expression profile of GSE72747 was used to screen out significant differently expressed genes (DEGs). Series Test of Cluster (STC) analysis for DEGs was performed. For all DEGs, the Database for Annotation, Visualization, and Integrated Discovery was performed for Gene Ontology (GO) enrichment analysis. Pathway enrichment analysis of DEGs was performed based on Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Pathway was constructed based on the interactions in the KEGG database. The coexpression network and gene signal expression networks were constructed and analyzed.

RESULTS

A total of 2193 DEGs were screened and eight significant profiles were identified. Significant GO terms included small molecule metabolic process, translation and apoptotic process. Metabolic pathways and Alzheimer's disease were significant KEGG pathways. Pathway relationship network of DEGs was constructed. MAPK signalling pathway, apoptosis and pathways in cancer were hub nodes. Gene co-expression network analysis was performed. VCP-interacting membrane protein and NADH dehydrogenase (ubiquinone) 1, alpha/beta subcomplex, 1, 8 kDa were the hub nodes. Gene signal network was constructed with 162 nodes and 254 edges. Hub nodes were phospholipase C, beta 2.

CONCLUSION

Screened DEGs including VIMP, NDUFAB1, SEC61G, PSMC2 might be potential targets for lupus nephritis treatment by involving in different functions and pathways, such as metabolic process and immune process.

Plasma Cell Depletion Attenuates Hypertension in an Experimental Model of Autoimmune Disease

Numerous studies show a direct relation between circulating autoantibodies, characteristic of systemic autoimmune disorders, and primary hypertension in humans. Whether these autoantibodies mechanistically contribute to the development of hypertension remains unclear. Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by aberrant immunoglobulin production, notably pathogenic autoantibodies, and is associated with prevalent hypertension, renal injury, and cardiovascular disease. Because plasma cells produce the majority of serum immunoglobulins and are the primary source of autoantibodies in SLE, we hypothesized that plasma cell depletion using the proteasome inhibitor bortezomib would lower autoantibody production and attenuate hypertension. Thirty-week-old female SLE (NZBWF1) and control (NZW [New Zealand White]) mice were injected IV with vehicle (0.9% saline) or bortezomib (0.75 mg/kg) twice weekly for 4 weeks. Bortezomib treatment significantly lowered the percentage of bone marrow plasma cells in SLE mice. Total plasma IgG and anti-dsDNA IgG levels were higher in SLE mice compared with control mice but were lowered by bortezomib treatment. Mean arterial pressure (mm Hg) measured in conscious mice by carotid artery catheter was higher in SLE mice than in control mice, but mean arterial pressure was significantly lower in bortezomib-treated SLE mice. Bortezomib also attenuated renal injury, as assessed by albuminuria and glomerulosclerosis, and reduced glomerular immunoglobulin deposition and B and T lymphocytes infiltration into the kidneys. Taken together, these data show that the production of autoantibodies by plasma cells mechanistically contributes to autoimmune-associated hypertension and suggests a potential role for patients with primary hypertension who have increased circulating immunoglobulins.

Lupus nephritis and B-cell targeting therapy

INTRODUCTION

Lupus Nephritis (LN) is a severe manifestation of Systemic Lupus Erythematosus (SLE) with a significant prognostic impact. Over a prolonged course, an exhaustion of treatment alternatives may occur and further therapeutic options are needed. B cells play a pivotal role in disease pathogenesis and represent an attractive therapeutic target. Areas covered: This review provides an update regarding targeting B cells in LN. The rational for this approach, as well as currently available and future targets are discussed. Expert commentary: Despite its wide clinical use and the encouraging results from retrospective studies, a role of rituximab in LN has not been prospectively confirmed. Trial design methodologies as well as intrinsic limitations of this approach may be responsible and rituximab use is currently limited as a rescue treatment or in settings where a strong steroid sparing effect is warranted. Despite belimumab now being licensed for use in SLE, the evidence in LN is weak although prospective trials are on-going. The combination of different targeted approaches as well as a focus on new clinical end-points may be strategies to identify new therapeutic options.

Bortezomib treatment induces a higher mortality rate in lupus model mice with a higher disease activity

Background

Bortezomib (Bz) is a proteasome inhibitor that directly targets antibody-producing plasma cells. We recently reported the first randomized control trial that evaluated the effects of Bz in patients with systemic lupus erythematosus (SLE). In that study, we demonstrated that Bz treatment is associated with many adverse reactions in patients with refractory disease. In the present study, we examine the therapeutic and toxic effects of Bz on MRL/MpJ-lpr/lpr (MRL/lpr) mice with severe disease activity.

Methods

Female MRL/lpr mice at 10 and 14 weeks of age were treated with phosphate buffered saline (PBS) (n = 19), Bz (750 μg/kg twice weekly) (n = 27), or cyclophosphamide (Cyc) (1 mg/body, once in 2 weeks) (n = 20). Cellular subsets, serum immunoglobulin, anti-double-stranded DNA (anti-dsDNA) antibody titer, and a pathological index of glomerulonephritis were then analyzed at 22 weeks of age. Survival curves of the 10-week-old and 14-week-old Bz-treated groups were compared. Blood counts, creatinine, liver enzymes, and serum cytokine levels were measured 1 week after Bz treatment. Gene expression profiling of spleens from Bz and Cyc treatment mice were compared with those from control mice.

Results

The anti-dsDNA antibody levels were significantly higher in 14-week-old than in 10-week-old mice, indicating a higher disease activity at 14 weeks. A significant decrease in the number of splenic cells and glomerulonephritis index was observed in Bz-treated and Cyc-treated mice. Bz, but not Cyc, significantly decreased serum immunoglobulin and anti-dsDNA antibody titer levels. Survival curve analysis revealed a significantly higher mortality rate in 14-week-old than in 10-week-old Bz-treated and control groups. Following two injections of Bz, serum IL-6 and TNF-α levels were significantly more elevated in 14-week-old than in 10-week-old mice. Potentially immunogenic molecules, such as heat shock proteins, were characteristically upregulated in spleens of Bz-treated but not Cyc-treated mice.

Conclusions

In spite of its therapeutic effect, Bz treatment had more toxic effects associated with increased proinflammatory cytokine levels in mice with a higher disease activity. Understanding the mechanism of the toxicity and developing preventive strategies against it is important for the safe clinical application of Bz in human SLE.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1397-7) contains supplementary material, which is available to authorized users.

Bortezomib followed by autologous stem cell transplantation in a patient with rheumatoid arthritis: A case report and review of the literature

RATIONALE AND PATIENTS CONCERNS

Despite the introduction of varied disease-modifying antirheumatic drugs and biological agents, a substantial proportion of patients remain untreatable. We report a 56-year-old Chinese female patient with a case of refractory rheumatoid arthritis (RA) complicated with multiple myeloma (MM) who was treated successfully with Bortezomib followed by autologous stem cell transplantation (ASCT).

DIAGNOSIS AND INTERVENTIONS

We report a 56-year-old Chinese female patient who was diagnosed as RA complicating with MM. She received 4 cycles of Bortezomib-based chemotherapy followed by ASCT. The response of her RA and MM were evaluated after every cycle of Bortezomib-based chemotherapy.

INTERVENTIONS AND OUTCOMES

After the first Bortezomib-based chemotherapy cycle, this patient's symptoms were significantly alleviated and thereafter the RA activity continued to improve. After the 4 courses of Bortezomib-based chemotherapy, the C-reactive protein was <0.5 mg/dL and the disease activity score 28-erythrocyte sedimentation rate was 2.0. No hematological or nonhematological side effects were observed during the treatment of Bortezomib.

LESSONS

Bortezomib might be a new safe and promising drug for refractory RA patients.

A pathophysiology-based approach to the diagnosis and treatment of lupus nephritis

Lupus is no longer an unknown chameleon of medicine. Significant progress has been made on unraveling the pathogenesis of lupus and lupus nephritis, and how to treat the disease. Here we provide an update on the pathophysiology of lupus and its related kidney disease, consider areas of controversy in disease management, and discuss the unmet needs of lupus nephritis and how to address these needs. We focus on rethinking how innovative therapies for lupus nephritis should be evaluated and evolving strategies to more efficiently mitigate irreversible nephron loss in patients with lupus nephritis.

Current and Emerging Therapies for Lupus Nephritis

The introduction of corticosteroids and later, cyclophosphamide dramatically improved survival in patients with proliferative lupus nephritis, and combined administration of these agents became the standard-of-care treatment for this disease. However, treatment failures were still common and the rate of progression to ESRD remained unacceptably high. Additionally, treatment was associated with significant morbidity. Therefore, as patient survival improved, the goals for advancing lupus nephritis treatment shifted to identifying therapies that could improve long-term renal outcomes and minimize treatment-related toxicity. Unfortunately, progress has been slow and the current approaches to the management of lupus nephritis continue to rely on high-dose corticosteroids plus a broad-spectrum immunosuppressive agent. Over the past decade, an improved understanding of lupus nephritis pathogenesis fueled several clinical trials of novel drugs, but none have been found to be superior to the combination of a cytotoxic agent and corticosteroids. Despite these trial failures, efforts to translate mechanistic advances into new treatment approaches continue. In this review, we discuss current therapeutic strategies for lupus nephritis, briefly review recent advances in understanding the pathogenesis of this disease, and describe emerging approaches developed on the basis of these advances that promise to improve upon the standard-of-care lupus nephritis treatments.

Bortezomib treatment prevents glomerulosclerosis associated with lupus nephritis in a murine model through suppressive effects on the immune and renin-angiotensin systems

OBJECTIVE

To clarify the mechanisms underlying lupus nephritis (LN) amelioration following bortezomib treatment.

METHODS

Bortezomib was administered subcutaneously every 3 days to NZB/W F1 mice, and the serum anti-double stranded (ds) deoxyribonucleic acid (DNA) antibody titers and proteinuria levels were measured. The renal samples and the splenocytes were examined histologically or used for real-time quantitative reverse transcription-polymerase chain reaction analysis after 18 weeks of treatment. Serum cytokine and anti-dsDNA antibody levels were measured using flow cytometry and enzyme-linked immunoassays every 3 weeks. Transforming growth factor (TGF)-β, angiotensin II type-1 receptor (AT1R), and type I collagen expression levels in the glomeruli were evaluated using immunohistochemistry.

RESULTS

Bortezomib reduced the serum anti-dsDNA antibody titers and the proteinuria levels. It prevented inflammatory cell infiltrations into and the deposition of immunoglobulin G within the glomeruli. Bortezomib reduced the interferon-γ, interleukin (IL)-4, and IL-10 levels in the serum and the ribonucleic acid expression levels for these cytokines within the splenocytes. Bortezomib prevented type I collagen synthesis by downregulating TGF-β and AT1R expression in the glomeruli.

CONCLUSIONS

Bortezomib exerts multiple immunosuppressive effects and thus ameliorates LN. Furthermore, bortezomib can prevent glomerulosclerosis formation in NZB/W F1 mice through suppressive effects on the renin-angiotensin system.

CD163+ M2c-like macrophages predominate in renal biopsies from patients with lupus nephritis

Background

The role of macrophages in the pathogenesis of lupus nephritis, in particular their differentiation to a certain subtype (e.g., M1- or M2-like) modulating the inflammatory reaction, is unknown. Here we investigated whether the differentiation in M1- or M2-like macrophages depends on the stage of lupus nephritis and whether this correlates with clinical parameters.

Method

Using immunohistochemical analysis we analyzed renal biopsies from 68 patients with lupus nephritis (ISN/RPS classes II–V) for infiltration with M1-like (iNOS+/CD68+), M2a-like (CD206+/CD68+), M2c-like macrophages (CD163+/CD68+), and FoxP3+ regulatory T-cells. In addition, clinical parameters at the time of renal biopsy, i.e., blood pressure, proteinuria and serum urea were correlated with the macrophage infiltration using the Spearman test.

Results

The mean number of CD68+ macrophages was related to the diagnosed ISN/RPS class, showing the highest macrophage infiltration in biopsies with diffuse class IV and the lowest number in ISN/RPS class V. In all ISN/RPS classes we detected more M2c-like CD163+/CD68+ than M2a-like CD206+/CD68+ cells, while M1-macrophages played only a minor role. Cluster analysis using macrophage subtype numbers in different renal compartments revealed three main clusters showing cluster 1 dominated by class V. Clusters 2 and 3 were dominated by lupus class IV indicating that this class can be further differentiated by its macrophage population. The number of tubulointerstitial FoxP3+ cells correlated with all investigated macrophage subtypes showing the strongest association to numbers of M2a-like macrophages. Kidney function, as assessed by serum creatinine and serum urea, correlated positively with the number of total CD68+, M2a-like and M2c-like macrophages in the tubulointerstitium. In addition, total CD68+ and M2c-like macrophage numbers highly correlated with Austin activity score. Interestingly, in hypertensive lupus patients only the number of M2a-like macrophages was significantly increased compared to biopsies from normotensive lupus patients.

Conclusion

M2-like macrophages are the dominant subpopulation in human lupus nephritis and particularly, M2a subpopulations were associated with disease progression, but their role in disease progression remains unclear.

Key issues in the management of patients with systemic lupus erythematosus: latest developments and clinical implications

Systemic lupus erythematous (SLE) is a chronic multisystem disease with significant associated morbidity and mortality. A deeper understanding of the pathogenesis of SLE has led to the development of biologic agents, primarily targeting B cells and others inhibiting costimulatory molecules, type I interferons and cytokines such as interleukin-6. Several of these agents have been studied in clinical trials; some have shown promise while others have yielded disappointing results. Economic and regulatory issues continue to hamper the availability of such therapies for SLE patients. With increasing recognition that recurrent flares of disease activity lead to long-term damage accrual, one of the most important recent developments in patient management has been the concept of treat-to-target in SLE while minimizing patient exposure to excessive corticosteroid and other immunosuppressive therapy. This article reviews these key issues in SLE management, outlining recent developments and clinical implications for patients.

Bortezomib-induced acute interstitial nephritis

Acute interstitial nephritis (AIN) is one of the important causes of acute kidney injury (AKI) resulting from inflammatory tubulointerstitial injury induced by medications, infections and systemic diseases. Bortezomib has been increasingly used especially in renal related indications such as multiple myeloma and monoclonal gammopathy of renal significance. Severe allergic reactions from bortezomib treatment including AIN have not been described in the literature. We report a 47-year-old white man who developed biopsy-proven allergic AIN after treatment with bortezomib for his C3 glomerulonephritis. The patient's kidney function improved after treatment with glucocorticoid therapy and discontinuation of bortezomib, but worsened with recurrent AKI episode after re-initiation of bortezomib. His renal function improved after glucocorticoid therapy and discontinuation of bortezomib. To our knowledge, this is the first report of a biopsy-proven AIN from bortezomib.

Review of bortezomib treatment of antibody-mediated rejection in renal transplantation

SIGNIFICANCE

Development of donor-specific antibodies (DSA) after kidney transplantation is associated with reduced allograft survival. A few strategies have been tested in controlled clinical trials for the treatment of antibody-mediated rejection (AMR), and no therapies are approved by regulatory authorities. Thus development of antihumoral therapies that provide prompt elimination of DSA and improve allograft survival is an important goal.

RECENT ADVANCES

Proteasome inhibitor (PI)-based regimens provide a promising new approach for treating AMR. To date, experiences have been limited to off-label bortezomib use in AMR. Key findings with PI-based therapy are that they provide effective primary and rescue therapy for AMR by prompt reduction in immunodominant DSA and improvements in histologic and renal function. Early and late AMR differ immunologically and in response to PI therapy. Bortezomib-related toxicities in renal transplant recipients are similar to those observed in the multiple myeloma population.

CRITICAL ISSUES

Although preliminary evidence with PI therapy for AMR is encouraging, the evidence is limited. Larger, prospective, randomized controlled trials with long-term follow up are needed. Advancement in endpoints of clinical trial designs and rigorous clinical trials with more standardized adjunct therapies are also required to explore the risks and benefits of AMR treatment modalities.

FUTURE DIRECTIONS

In the next few years, new PIs are likely to be introduced and new approaches would be developed for achieving synergy with PIs. The ultimate goal will be to develop a regimen that delivers reliable, rapid, complete, and durable elimination of DSA with an acceptable safety profile.

Targeting B cells and autoantibodies in the therapy of autoimmune diseases

B cells and B cell-derived autoantibodies play a central role in the pathogenesis of many autoimmune diseases. Thus, depletion of B cells via monoclonal antibodies such as Rituximab is an obvious therapeutic intervention and has been used successfully in many instances. More recently, novel therapeutic options targeting either the autoantibody itself or resetting the threshold for B cell activation have become available and show promising immunomodulatory and anti-inflammatory effects in a variety of animal models. The aim of this review is to summarize these results and to provide an insight into the underlying molecular and cellular pathways of these novel therapeutic interventions targeting autoantibodies and B cells and to discuss their value for human therapy.

Lupus nephritis: the evolving role of novel therapeutics

Immune complex accumulation in the kidney is the hallmark of lupus nephritis and triggers a series of events that result in kidney inflammation and injury. Cytotoxic agents and corticosteroids are standard of care for lupus nephritis treatment, but are associated with considerable morbidity and suboptimal outcomes. Recently, there has been interest in using novel biologic agents and small molecules to treat lupus nephritis. These therapies can be broadly categorized as anti-inflammatory (laquinamod, anti-tumor necrosis factor-like weak inducer of apotosis, anti-C5, and retinoids), antiautoimmunity (anti-CD20, anti-interferon α, and costimulatory blockers), or both (anti-interleukin 6 and proteasome inhibitors). Recent lupus nephritis clinical trials applied biologics or small molecules of any category to induction treatment, seeking short-term end points of complete renal response. These trials in general have not succeeded. When lupus nephritis comes to clinical attention during the inflammatory stage of the disease, the autoimmune stage leading to kidney inflammation will have been active for some time. The optimal approach for using novel therapies may be to initially target kidney inflammation to preserve renal parenchyma, followed by suppression of autoimmunity. In this review, we discuss novel lupus nephritis therapies and how they fit into a combinatorial treatment strategy based on the pathogenic stage.

New approaches for the treatment of lupus nephritis in the 21st century: from the laboratory to the clinic

Systemic lupus erythematosus is a complex autoimmune disorder affecting multiple organ systems. Glomerulonephritis leading to severe proteinuria, chronic renal failure and end-stage renal disease remains one of the most severe complications of systemic lupus erythematosus and is associated with significant morbidity and mortality. Conventional lupus nephritis (LN) treatment based on cyclophosphamide, steroids and, recently, mycophenolatemofetil has improved the outcome of the disease over the last 50 years, although failure to achieve remission or treatment resistance has been reported in 18–57% of patients. Chronic complications such as long-term toxicity dampen their ability to maintain disease remission. There is a need to develop more specific pharmacological agents for patients to provide choices that are equally effective, less toxic and have fewer complications. During the last 10 years, experimental studies based on different pathogenesis pathways of LN have provided an enormous amount of knowledge and have offered the possibility to target the disease with selective approaches. In this article, we summarize the new experimental strategies that have recently been utilized to target LN, focusing on mechanisms of action.

Small molecules in the treatment of systemic lupus erythematosus

Advances in the understanding of the cellular biological events that underlie systemic lupus erythematosus (SLE) have led to the identification of key molecules and signaling pathways that are aberrantly expressed. The parallel development of small molecule drugs that inhibit or interfere with the specific perturbations identified, offers perspective for more rational, effective and less toxic therapy. In this review, we present data from preclinical and clinical studies of such emerging novel therapies with a particular focus on kinase inhibitors and other compounds that modulate signal transduction. Moreover, we highlight the use of chromatin-modifying medications, bringing attention to the central role of epigenetics in SLE pathogenesis.

Proteasome inhibition prolongs survival during lethal hemorrhagic shock in rats

BACKGROUND

Several lines of evidence suggest that proteasomes, the major nonlysosomal proteases in eukaryotes, are involved in the pathophysiology of various disease processes, including ischemia-reperfusion injury and trauma. Recently, we demonstrated that 26S proteasome activity is negatively regulated by adenosine triphosphate (ATP) and that proteasome activation during ischemia contributes to myocardial injury. The regulation of tissue proteasome activity by ATP and the potential of proteasomes as drug targets during hemorrhagic shock, however, are unknown. Thus, we evaluated the regulation of tissue proteasome peptidase activity and the effects of the proteasome inhibitor bortezomib in rat models of hemorrhagic shock.

METHODS

Series 1 includes animals (n = 20) hemorrhaged to a mean arterial blood pressure of 30 mm Hg for up to 45 minutes. Series 2 includes animals hemorrhaged to a mean arterial blood pressure of 30 mm Hg for 30 minutes, followed by bortezomib (0.4 mg/kg) or vehicle administration (n =5 per group) and fluid resuscitation until 75 minutes. Series 3 includes animals that underwent 40% blood volume hemorrhage, followed by 2% blood volume hemorrhage every 15 minutes until death. Bortezomib (0.4 mg/kg) or vehicle were administered 15 minutes after the onset of hemorrhage (n = 6-7 per group). Vital signs were continuously monitored. The heart, lung, and pectoral muscle were analyzed for proteasome peptidase activities and levels of ATP, ubiquitin-protein conjugates, and cytokines (tumor necrosis factor α, interleukin 6, and interleukin 10).

RESULTS

In Series 1, proteasome peptidase activities in tissue extracts increased proportional to the decrease in tissue ATP concentrations during hemorrhagic shock. Activation of proteasome peptidase activity with decreases of the ATP assay concentration was also detectable in normal tissue extracts. In Series 2, systemic administration of bortezomib inhibited tissue proteasome activities but did not affect the physiologic response. In Series 3, bortezomib inhibited tissue proteasome activities, increased endogenous ubiquitin-protein conjugates, and prolonged survival time from treatment from 48.5 minutes in the control group to 85 minutes (p = 0.0012). Bortezomib treatment did not affect tissue cytokine levels.

CONCLUSION

Proteasome activation contributes to the pathophysiology of severe hemorrhagic shock. Pharmacologic inhibition of the proteasome may provide a survival advantage during lethal hemorrhagic shock.

Cell death and cytokine production induced by autoimmunogenic hydrocarbon oils

Hydrocarbon oils such as pristane or hexadecane induce arthritis and lupus in rodents sharing clinical and pathological features with the human diseases rheumatoid arthritis and systemic lupus erythematosus, respectively. In pristane-induced lupus in the mouse induction of apoptosis and augmentation of type-I Interferon signalling by pristane have been suggested to contribute to pathology, whereas in pristane-induced arthritis (PIA) in the rat the pathological mechanisms are still elusive. Here we show that pristane induces cell death in rat and human cells. Increased numbers of apoptotic cells were found in draining lymph nodes of pristane-injected rats and increased percentages of apoptotic and necrotic cells were observed in peripheral blood. In addition, neutrophil extracellular trap formation was triggered by pristane and hexadecane in neutrophils. Because levels of interleukin (IL)-1β were elevated in sera of pristane-injected rats, with levels mirroring the course of PIA, we examined the effect of pristane at single cell level in vitro, using rat splenocytes and the human monocytic cell line THP-1. Pristane and other hydrocarbon oils induced IL-1β secretion in THP-1 cells as well as in rat splenocytes. The potassium channel inhibitor glibenclamide partly inhibited IL-1β induction, suggesting involvement of the inflammasome. Elevated levels of IL-1α were also found in supernatants of cells treated with pristane and hexadecane. In conclusion, autoimmunogenic hydrocarbon oils induce various forms of cell death in rat and human cells. The higher serum IL-1β levels in pristane-injected animals might be caused by both inflammasome-dependent and -independent mechanisms, such as passive release from dying-cells and probably extracellular maturation of pro-IL-1β.

Emerging therapies for systemic lupus erythematosus--focus on targeting interferon-alpha

Current therapies for systemic lupus erythematosus (SLE), a debilitating, potentially lethal, multifactorial systemic autoimmune disease, are limited to suppressing disease activity and are associated with multiple adverse effects. Recent advances in basic and translational sciences have elucidated a crucial role for the interferon-alpha (IFNα) pathway in the pathogenesis of this enigmatic disease. The so-called "type I interferon signature" has emerged as a major risk factor for disease activity of SLE. Multiple genes encoding for molecules within the type I interferon pathway have been associated with SLE in genome wide association studies. In addition, innate immune receptors are thought to be triggered by either endogenous and/or exogenous stimuli that lead to hypersecretion of IFNα. We review the multiple emerging treatment strategies targeting IFNα-related pathways. These include monoclonal antibodies against IFNα, anti-IFNα antibody-inducing vaccines, and inhibitors of Toll-like receptors. We also summarize the current status of these pharmaceutical agents in early clinical trials.